Rare earth magnets, sometimes known as permanent magnets, consist of alloys made from rare earth elements. Most of the time, the elements used are from the lanthanide series and alloys. The term rare earth is derived from the fact that the metals used to make the magnets can be abundantly found in the earth’s crust. However, the term rare earth can also be confusing because the metals, in this case, are neither rare nor precious. The metals are usually highly abundant. This post focuses on the basics of rare earth magnets.
Rare earth magnets are generally highly fragile. They also do not do well when they are exposed to humidity as they develop rust and corrosion. However, to enhance the durability of the magnets, rare earth magnets are usually coated or plated. Doing this protects them from breaking and getting damaged by humidity.
The history of rare earth magnets
Rare earth magnets were discovered in the 1970s and 1980s. However, their development started in 1966. At the time, they were found to be the strongest type of permanent magnet in existence. This is because these magnets produce a magnetic field that is way stronger than any other type of magnet. Before discovering rare earth magnets, alnico and ferrite magnets were known as the strongest on the market. Alnico and ferrite magnets feature magnetic fields of 0.5 and 1.0 teslas, respectively. On the other hand, rare earth magnets feature a magnetic field of more than 1.4 teslas.
Magnetism and strength
Rare earth elements are known for their ferromagnetism. Ferromagnetism is the fundamental mechanism by which specific materials are attracted to magnets. This means that the elements can be magnetized to become permanent magnets via exposure to a magnetic field. The magnetic strength of rare earth metals can be attributed to the following;
- The crystalline nature of their structures which have a significantly high magnetic anisotropy as rare earth metals are made up of microcrystalline jots, which are ranged in a strong magnetic field at the manufacture
- The high magnetic moments of their atoms ensure less magnetic cancellation
Types of rare earth magnets
The following are the two primary types of rare earth magnets;
- Samarium-cobalt rare earth magnets- these are the first group of rare magnets to be discovered. However, they are not as commonly used because they are more costly, and their magnetic strength is typically weaker. They are also more vulnerable to chipping and cracking. However, these magnets are highly resistant to oxidation.
- Neodymium rare earth- this group of magnets was discovered in the 1980s. They are the most affordable type of rare earth magnet on the market. They are also the strongest form of rare earth metals. They are manufactured from iron alloy, neodymium, and boron. They are also highly resistant to demagnetization. The downside to these rare earth metals is that they are prone to corrosion.
Neodymium rare earth magnets are the most common types of magnets currently on the market. They are used for commercial and industrial applications. The best neodymium rare earth magnet manufacturers usually coat and plate their products to enhance their durability. They are also manufactured in a wide range of sizes and shapes, depending on the application.